#include <stdio.h>

#ifndef __MYHEAD_H__
#define __MYHEAD_H__


// 头文件正文
struct node
{
    int a;
    char b;
};

#endif

// 表达一些互斥的量
union attr
{
    int x;
    char y;
    double z;  
};

struct node
{
    int a;
    char b;
    double c;
    union attr at; // at内有三种互斥的属性，非此即彼
};

int main(int argc, char const *argv[])
{
    struct node n;

    n.at.x = 100;
    n.at.y = 'x';

    printf("%ld\n", sizeof(union attr));

    return 0;
}

